1. Field of the Invention
The present invention relates to a metal core for a steering wheel, to be used for automobiles, and more specifically to a steering wheel core in which a plurality of metal pipe core elements in circular arc form are connected by connecting metal core elements of a prescribed number whereby a ring core is formed, and spoke cores are connected at respective radially outer ends to the connecting core elements of the ring core and at respective radially inner ends to a boss plate.
2. Description of the Prior Art
In such a steering wheel metal core of the prior art, a part of a ring core is formed a by pipe so as to make the metal core lighter in weight, a plurality of pipe core elements in circular arc form are connected by connecting core elements of a prescribed number, and thereby a ring core is formed. In this case, connection of the pipe core elements with the connecting core elements has been performed in a process in which the pipe core elements are arranged outside the connecting core elements and end circumferential surface of each pipe core element is welded to each connecting core element.
However, simultaneous welding of the whole circumference at ends of the pipe core elements is difficult because the welding may be obstructed by other portions. Consequently, the whole circumference is divided into three or the like during the welding. For example, when the ring core is composed of the three pipe core elements, the connecting core elements also become three in number and each pipe core element is welded at both ends. That is, the six portions must be welded by dividing in three respectively and therefore the process number becomes large for the connection.
Since welding is utilized in order to connect the pipe core elements to the connecting core elements, both core elements cannot be connected to each other if both are made of different materials, for example, if the connecting core elements are made of iron and the pipe core elements are made of aluminium to make the core metal lighter in weight.